In order to comply with International Maritime Organisation (IMO) gas emission regulations to be implemented in ECAs (Emission Control Areas), several technologies have been developed to remove the harmful pollutants from exhaust gas as a result of combusting fossil fuel in marine engines, boilers and incinerators.
Information relating to existing apparatus and methods for treating exhaust gas can be found in the following publications:
U.S. Pat. No. 3,793,809 (Tomany et al.) discloses a venturi type scrubber for fine particles removal in which gaseous stream is fed co-currently with liquid spray from a top centre feed venturi throat, and further removal is enhanced by reversing the gas flow and force it through a loosely packed packing sections. At the final stage, a plurality of vane type passage is provided to remove any entrained liquid mists.
U.S. Pat. No. 5,759,233 (Schwab) discloses a vertically positioned venturi throat concept where the particle laden gas is introduced through the bottom opening of the means so that the gas and liquid spray are flowing upward towards the exit of the means, facilitating connection to an exhaust gas fan. It is highlighted that the liquid flow is controlled in order not to affect the droplet size.
U.S. Pat. No. 6,036,756 (Gohara et al.) discloses a top centre feed type scrubber where the effectiveness is enhanced by the perforated section located at the bottom of a run-down pipe, where the pollutant laden gas reverses and enters the absorption zone included in the annulus space between run-down pipe and the scrubber external shell.
Currently, proper design for shipboard installation is relatively few when retrofitting, footprint, weight, back pressure and performance under motion are considered. Accordingly, improved apparatus and method for treating exhaust gas to remove water soluble pollutants such as sulphur oxides (SOx), particulate matter (PM) and unburned hydrocarbons are highly desirable.